HVAC quote red flags

None of these means you are being cheated. Each one means there is something the quote has not told you, and a question you can ask in one sentence. These are the nine our review fires on, with what each usually turns out to be.

1. No load calculation

The big one. If sizing came from the existing system or a square-footage rule, nobody has established what your house actually needs — and if the old system was wrong, the new one inherits the error. DOE's position is that rules of thumb are what produce oversized systems.

Ask: "Will you perform a Manual J load calculation before we finalise the size, and can I have a copy?"

2. Your quotes disagree on capacity

When one contractor says 3 tons and another says 4 for the same house, at most one is right. Usually it means neither measured, and both defaulted — one to the existing size, one to "bigger is safer". Bigger is not safer: an oversized system cools fast, shuts off, and leaves the house clammy.

Ask: "Another quote I have is a different capacity — how did you arrive at yours?"

3. Efficiency below the federal minimum

Since 2023 new equipment must meet a minimum SEER2, and the minimum is higher in the southeast and southwest than in the rest of the country. Nine times in ten a below-minimum figure on a quote is a transcription error; occasionally it is old stock that cannot lawfully be installed new.

Ask: "The rating on the quote is below the federal minimum for my state — can you confirm the exact model and its SEER2?"

4. No model numbers

"High-efficiency 3-ton system" is not a specification. Without the outdoor unit, coil and furnace model numbers you cannot check the rating, the warranty, or that what arrives on the truck is what you bought.

Ask: "Please put the exact model numbers on the quote before I sign."

5. Permit not mentioned

Most jurisdictions require a permit for a replacement, and the inspection that comes with it is free quality control that you have already paid for. A quote silent on permits is either including it and not saying so, or not pulling one.

Ask: "Is a permit required here, is it in this price, and who pulls it?"

6. A wide spread between quotes

Not proof of overcharging — usually proof that the quotes cover different work. Finding out which parts differ is more useful than assuming the low one is the bargain.

Ask: "What does your price include that a cheaper quote might not?"

7. Only one quote

With nothing to compare against, nobody can tell you whether a price is normal for your area. Two more quotes is the highest-value hour available on a five-figure decision, and it is free.

8. Nothing in writing

A verbal number is not a quote. It cannot be compared, held to, or referred back to when the invoice differs.

Ask: "Can I have this in writing, itemised, before I decide?"

9. Pressure

A price that expires today, a large deposit demanded before any work, being told not to bother getting other quotes, or heavy financing pressure. These are sales techniques. They are not facts about the equipment, and a good contractor's price will still be there next week.

Ask: "Will this price still be available next week?"

What red flags are not

Every one of these is a prompt for a conversation. A contractor who has been in your attic may have an excellent answer — that the ducts cannot carry more air, that the panel will not take the load, that the previous system was genuinely undersized. The purpose of a flag is to make sure that answer gets said out loud before you commit, not to decide anything for you.

Check my quotes against all nine — $49

Informational only. Not a load calculation and not an engineering report.